For most cities including LA, the "Union" in Union Station indicates that the station serves as the unified train station for the city meaning all trains no matter what the railway come to that station. But in Chicago that's not the case, now or in the past.
Now days Union Station is the central station for all cross country trains, but not all passenger trains in Chicago come here. Metra, Chicago's massive commuter train service has trains that come to Union Station, but also trains that go to other stations following the heritage of the original railways that are now part of the Metra system. Of course it has long been noted that when it comes to Union Station the relationship between Metra and Amtrak is at times strained, especially since Amtrak controls the station dispite Metra having more trains operate out of the station every single day.
Metra is an interesting case and point about the original stations and rail lines that came into the city of Chicago in the past, since Metra still operates at a lot of those stations either in the original form or more modern reincarnations. Or to put it another way if you want to experience the terminals and sites of historic American passenger trains Metra may provide you with a living examples, something your not likely to see anywhere else.
Historically and in a very real modern sense Chicago is and has been the railroad hub of the United States for well over a hundred years. This means that there are hundreds of rail lines coming into the city from all directions. For the great Eastern railways that there where and are, Chicago was a the Western Terminus, for the Western Railways the Eastern terminus, and the same could be said for the Northern railways of Canada with a Southern end, and Southern with a Northern end. One can only imagine that with trains coming in on multiple tracks from all directions, the concept of a central station would cause severe rail gridlock as trains converged on one point. So Chicago would need to accomdate passenger trains with more then one station.
For most railroads this wasn't to their dislike. A railroad station built for their specific needs, could show off the railways affluence, and market the railway to its captive audience of passengers. Ornate woodwork, gold leaf fixtures, marble floors and columns, and a plethora of top quality restaurants and passenger service stores allowed railways to instill a feeling of luxury, and service to passengers, and others passing through the stations.
Union Station Chicago is an excellent example of railway architecture and interior design for stations during the golden era of train travel.
In the height of the rail travel era Chicago was served by 6 major train stations:
-Union Station that served the Chicago, Burlinton, and Quincy, Milwaukee Road, and Pennsylvania Railways, and several smaller lines.
Union Station today, in the right of the picture above the "bacon" truck you can see part of the office building stucture that replaced the terminal building.
-Northwestern Station which served the Chicago Northwestern, B&O, Union Pacific, and smaller lines.
-Lasalle Street Station that served the New York Central and played a major part in Hitchcocks North by Northwest. Lasalle Street also served the Rock Island.
-Central Station which served the Illinois Central, C&O, and smaller lines
-Dearborn Station which famously served the Santa Fe, as well as the Grand Trunk, Erie, Monon, and Wabash.
-Grand Central Station which also served that B&O, SOO, and smaller lines.
Of the six stations only Union Station remains in its original form both in structure and operation. Or I should mention that its Grand Hall still stands which is the true show piece of the station. The terminal structure that stood accross Canal Street from it was replaced with an office complex in the 1960's.
Old postcard depicts the entire Union Station complex as it was. Only the larger building in back the "Grand Hall" still stands, but it is a functional structure that accommodates thousands of passengers daily.
Picture of above street platform from original structure, taken from Clinton side, looking at Randolph overpass.
Dearborn Station also still stands but it's railway history is long gone. The building is in good shape and has a restaurant, a few small stores, and professional offices in it. Any sign that this building was once a home to such legendary trains as Santa Fe's Super Chief are long gone.
Central Station is no longer and was demolished in 1974. However, Central Stations legacy lives on at Millenium Station which lies below Chicago's Millenium Park, beneath that "Bean" and "Pritzker Pavillion". Millenium Station still serves Illinois Centrals electric line, now part of Metra. You might have seen Millenium Station in "The Dark Knight", as Batman raced his Batbike through it.
Northwestern Station operates as part of Metra/Union Pacific Railway. However the original station structure was demolished in 1984 and replaced with a towering office building, that has hints of the original structure still in it. Ogilvie Station as it is now called, still has the original platform and overpass from the C&NW in place.
The station itself though is very modern and geared toward the thousands of commuters who pass through daily with grab and go shopping and food court
Grand Central Station on the other hand is totally gone and nothing but a vacant lot remain, sadly it was ripped down in
1969, and has no surviving lagacy.
Lasalle Station like Ogilvie exists but has been modernized with original parts of the structure ripped down and replaced for the lucrative air rights in 1981. So don't go looking for where Cary Grant shaved in North by Northwest that part is long gone. But the station survives and is operated by Metra for its Rock Island district.
Lasalle Street Station as it now looks
So of the six stations from the golden era only one stands as is and is functional, one stands but no longer as a station, one is totally gone, two stand in their original spots but rebuilt and modernized, and one is gone but had its place taken elsewhere. But that also means Chicago has four train stations that see thousands of passengers a day, three which operate in the same spots they did long ago.
If you want to see living history, and the legacy of what once was Metra can accommodate you at Union, Ogilvie, LaSalle and Millenium Station, and Amtrak can too at Union Station. If your visiting Chicago as a Route 66 follower and/or a railfan be sure to check at least one of these stations out, and if possible take a short ride on one of Metra's trains.